In recent years, bit-interleaved coding and modulation (hereinafter, BICM) systems have been used in the field of digital communications (see, for example, Non-Patent Literature 1).
BICM systems generally incorporate the following three steps.    (1) Encoding data blocks into codewords using, for example, quasi-cyclic low-density parity check (hereinafter, QC LDPC) code or similar.    (2) Performing bit interleaving on the bits of each codeword.    (3) Dividing each bit interleaved codeword into constellation words having a number of constellation bits, and mapping the constellation words to constellations.